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post #2101 of 2533 Old 07-17-2017, 01:28 PM
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Originally Posted by Floyd Toole View Post
RE identical LCRs. NO doubt this is ideal. but this person has a dilemma - the speakers he wants won't fit his small room. A phantom center is vastly worse than a slightly phase mismatched center speaker.

Unless the center speaker is exactly the same as the L & R and at the same elevation, there is a high probability of some phase mismatching (reflections from surfaces near either the loudspeaker or the listener, combined with the direct sound, alter phase). Many/most/all? of us have lived with that. Ignorance is bliss.

These phase effects are only audible when sounds radiate from two of more of the LCRs, creating phantom images between them. This happens most often in panned motion effects. Positionally stable panned phantom image locations really only are reliable for the mixer at the center of the console or listeners on the center line of the cinema or home theater. I'm told that they are discouraged. That said, some music videos do the disgusting thing of radiating the featured artist from all three speakers. Talk about phase effects, especially for anyone not on the center line. Go figure. Fortunately, humans are insensitive to those kinds of phase effects.

If the customer is in love with M2s and listens in stereo a lot of the time, a non-identical center is a compromise worth considering. However three "identical" loudspeakers is of course the preferred solution.
How about center m2 horizontal, I would like your opinion on this Mr.Toole as I Amin love with the M2's and have a solid screen with only 21" below for center. I've asked this of John and also Harman synthesis but would like your opinion. The other surround and cieling speakers are 708i's. The room is 18x18, and the screen is 14' wide.

Lastly with a move toward fixed tile panels in the future for both cinema and home theater what if any plans does Harman have to address the center channel speaker/s.
Thanks

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post #2102 of 2533 Old 07-17-2017, 01:46 PM
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Are the 708p sufficient for a room that is 20 x 19 x 10?

Here is what I am exploring to do a 9.4.4 with 708P for the front and 705P for all the others?
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post #2103 of 2533 Old 07-17-2017, 01:51 PM
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Are the 708p sufficient for a room that is 20 x 19 x 10?

Here is what I am exploring to do a 9.4.4 with 708P for the front and 705P for all the others?
For speakers it depends more on listening distance than room size. What are those distances?
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post #2104 of 2533 Old 07-17-2017, 02:18 PM
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Originally Posted by LJG View Post
How about center m2 horizontal, I would like your opinion on this Mr.Toole as I Amin love with the M2's and have a solid screen with only 21" below for center. I've asked this of John and also Harman synthesis but would like your opinion. The other surround and cieling speakers are 708i's. The room is 18x18, and the screen is 14' wide.

Lastly with a move toward fixed tile panels in the future for both cinema and home theater what if any plans does Harman have to address the center channel speaker/s.
Thanks
Before deciding to go the Revel route, substantially because of visual aesthetics in our room, I gave serious thought to M2s. I have a 65 inch flat screen with space behind it, and a drop down 10 ft screen. The center channel had to be below the flat screen. I had the option of standing the center M2 on its head, or laying it on its side. I probably would have gone the "on its head" route simply for consistency - the L and R would also have been inverted, as are my Salon 2s. To answer your question, I can think that the only issue with either of the options is that the center loudspeaker is closer to the floor than the L & R - as is my Voice2 right now. Does it matter? Frankly, I am not aware of any problem. The system simply is impressive in every respect. But, then that is me with my old (but still pretty fussy) ears :-)
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post #2105 of 2533 Old 07-17-2017, 02:26 PM
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Thanks for the replies to my post.

If I, and most likely I will, go with the 708i all around route with a large TV, should all the floor level speakers be at the same height? Should the side and back surrounds be the same height as the LCR speakers? What if the front left and right speakers are slightly lower than the center speaker (which will be just above the TV)? If I place the front left and right speakers in line with the center speaker, the LCR speakers will be higher than the TV.
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post #2106 of 2533 Old 07-17-2017, 02:31 PM
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For speakers it depends more on listening distance than room size. What are those distances?
I trust that bass management will be used. If so, all loudspeakers will be high-pass filtered. Whatever maximum sound output is specified, the one that matters is the capability when frequencies below 80 Hz are removed. Commonly the specified output is limited by woofer displacement/power handling. One would sensibly offload that stress to multiple subwoofers. I have high pass filtered my Revel Salon2s as I would have M2s, if I had gone that route.
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post #2107 of 2533 Old 07-17-2017, 03:12 PM
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Originally Posted by Floyd Toole View Post
Whatever maximum sound output is specified, the one that matters is the capability when frequencies below 80 Hz are removed. Commonly the specified output is limited by woofer displacement/power handling. One would sensibly offload that stress to multiple subwoofers.

Forgive my confusion, but does this mean that the maximum output of high-passed speakers are limited by woofer displacement/power handling? My confusion is that I thought maximum tweeter power handling was generally the limiting factor in a bass-managed system, since the woofers on the high-passed speaker is relieved of most of it's work. This allows the high-passed speakers to play *much* louder, or alternately, the same SPL but less distortion.

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post #2108 of 2533 Old 07-17-2017, 03:28 PM
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Originally Posted by Floyd Toole View Post
Before deciding to go the Revel route, substantially because of visual aesthetics in our room, I gave serious thought to M2s. I have a 65 inch flat screen with space behind it, and a drop down 10 ft screen. The center channel had to be below the flat screen. I had the option of standing the center M2 on its head, or laying it on its side. I probably would have gone the "on its head" route simply for consistency - the L and R would also have been inverted, as are my Salon 2s. To answer your question, I can think that the only issue with either of the options is that the center loudspeaker is closer to the floor than the L & R - as is my Voice2 right now. Does it matter? Frankly, I am not aware of any problem. The system simply is impressive in every respect. But, then that is me with my old (but still pretty fussy) ears :-)
Thank you for responding and another confirmation, I look forward to implementing this.
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post #2109 of 2533 Old 07-17-2017, 03:49 PM
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Forgive my confusion, but does this mean that the maximum output of high-passed speakers are limited by woofer displacement/power handling? My confusion is that I thought maximum tweeter power handling was generally the limiting factor in a bass-managed system, since the woofers on the high-passed speaker is relieved of most of it's work. This allows the high-passed speakers to play *much* louder, or alternately, the same SPL but less distortion.
Maybe I created the confusion, sorry if I did. What I tried to say was that the maximum sound output from a loudspeaker system is often limited by the excursion limit/power handling/distortion of the woofer. This assumes that it is being driven by a full bandwidth signal. As can be imagined, there are enormous abuses to such a rating system, a simple one being to band limit the test signal to avoid having the voice coil banging against the stops. Then there is the duration of the output; does it catch fire after a few minutes at the specified level. And so on. There are some disturbing revelations in an article called "Spec Wars: Looking Inside Loudspeaker SPL Specifications" - Google it and read it from www.prosoundweb.com.

However whatever merit the initial sound output claims may have, when bass management is invoked, the woofer has much less work to do, all at higher frequencies where displacements are smaller. The system can play significantly louder. Then, it may well be the tweeter, or the midrange distortion or power handling, that becomes the limiting factor. It will vary among loudspeaker designs. So, you are right.
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post #2110 of 2533 Old 07-17-2017, 04:04 PM
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Originally Posted by Kain View Post
Thanks for the replies to my post.

If I, and most likely I will, go with the 708i all around route with a large TV, should all the floor level speakers be at the same height? Should the side and back surrounds be the same height as the LCR speakers? What if the front left and right speakers are slightly lower than the center speaker (which will be just above the TV)? If I place the front left and right speakers in line with the center speaker, the LCR speakers will be higher than the TV.
The elevation of a sound is perceptually defined by the source of high frequencies - the tweeter or horn. We are very poor at vertical localization (our ears are in the wrong places) so great precision cannot be expected, which means that we tend to be quite tolerant of "errors". In your case place the L & R at a level where the soundstage is appropriate for the picture. If the center must be above the screen invert it so that the tweeter/horn is as close to the screen as possible. Do the reverse if it is below. The ventriloquism effect and human adaptation will take care of the rest. Enjoy.

Surround speakers in 5.1 and 7.1 systems tend to be located with the tweeter/horns about 2 ft (0.6 m) above ear level. It is a good compromise for movies and music.

With the appearance of huge LCD screens, some cinemas will now have LCR loudspeakers above the screens. That was also true for some of the older very widescreen cinemas that did not have perforated screens.
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post #2111 of 2533 Old 07-17-2017, 07:30 PM
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Originally Posted by Floyd Toole View Post
I trust that bass management will be used. If so, all loudspeakers will be high-pass filtered. Whatever maximum sound output is specified, the one that matters is the capability when frequencies below 80 Hz are removed. Commonly the specified output is limited by woofer displacement/power handling. One would sensibly offload that stress to multiple subwoofers. I have high pass filtered my Revel Salon2s as I would have M2s, if I had gone that route.
Correct, I had assumed bass management for an HT theater with 7 series speakers. With the 7 series the woofer is the limiting driver, not the CD. Whereas the Salon 2 appears limited by it's tweeter, not the woofer.

The M2 is limited by my ears , although I know at some point it's woofer would be the limiting driver.
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post #2112 of 2533 Old 07-17-2017, 10:15 PM
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When serious hearing loss is involved, we take what we can get, and are grateful for anything that gives pleasure.

When it is gone, it is gone. I have people close to me with hearing issues - and me with my tinnitus. However, I still hear quite well in spite of it, and get great pleasure from music and movies.
Although I wouldn't hold out too much hope, there is a sliver of chance it may not be permanent after all.

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post #2113 of 2533 Old 07-17-2017, 10:46 PM
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Yes, yes, yes! Only caveat was that Charles Sprinkle suggested that a 708 center paired with M2s may not be ideal, due to the following:

The problem with using three non-identical speakers for LCR (say, two M2s for L/R and one LSR708 for center) has to do with the phase being non-linear. This can be corrected with a processor using FIR filters, but will create latency issues.


Any input?

I've been suggesting 708s for Kain's room but it has been controversial here...


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post #2114 of 2533 Old 07-18-2017, 02:40 AM
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Great 4722 Be but can't fit Kain's room.
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post #2115 of 2533 Old 07-18-2017, 05:14 AM
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Originally Posted by Floyd Toole View Post
The elevation of a sound is perceptually defined by the source of high frequencies - the tweeter or horn. We are very poor at vertical localization (our ears are in the wrong places) so great precision cannot be expected, which means that we tend to be quite tolerant of "errors". In your case place the L & R at a level where the soundstage is appropriate for the picture. If the center must be above the screen invert it so that the tweeter/horn is as close to the screen as possible. Do the reverse if it is below. The ventriloquism effect and human adaptation will take care of the rest. Enjoy.

Surround speakers in 5.1 and 7.1 systems tend to be located with the tweeter/horns about 2 ft (0.6 m) above ear level. It is a good compromise for movies and music.

With the appearance of huge LCD screens, some cinemas will now have LCR loudspeakers above the screens. That was also true for some of the older very widescreen cinemas that did not have perforated screens.
Hi again Floyd, can you or John elaborate on the "Sculptured Surround System Sound System" provided by JVC for Samsung Cinema LED screen installed in Super S theater in South Korea? If we are indeed going with fixed LED screens in the future what does JBL have planned/in store for its parent company Samsung?, or for any future fixed LED or solid screen installs?
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post #2116 of 2533 Old 07-18-2017, 05:36 AM
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That is certainly a great looking FR, but is beating the response into submission at the listening position with DSP a good idea? It seems to me that there will be a lot of unnecessary correction that could impact SQ negatively?

In other words, how do you know what should or shouldn't be corrected at the LP? This is much different than correction of the anechoic response.
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post #2117 of 2533 Old 07-18-2017, 06:04 AM
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I think that is a near-field measurement
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post #2118 of 2533 Old 07-18-2017, 06:49 AM
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I think that is a near-field measurement
It says at "@ listening position" on the graph
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post #2119 of 2533 Old 07-18-2017, 07:30 AM
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Correct, I had assumed bass management for an HT theater with 7 series speakers. With the 7 series the woofer is the limiting driver, not the CD. Whereas the Salon 2 appears limited by it's tweeter, not the woofer.

The M2 is limited by my ears , although I know at some point it's woofer would be the limiting driver.
I wouldn't think the Salon 2 tweeter would be an issue unless you like it really loud. Most Be tweeters that I have seen have sensitivity in the 90s and low Fs. I would think the 2300hz crossover point wouldn't be stressing it that much. I understand what you are saying though.

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post #2120 of 2533 Old 07-18-2017, 07:50 AM
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I wouldn't think the Salon 2 tweeter would be an issue unless you like it really loud. Most Be tweeters that I have seen have sensitivity in the 90s and low Fs. I would think the 2300hz crossover point wouldn't be stressing it that much. I understand what you are saying though.
Depends on what you consider really loud. 95 dB is loud, but not really loud.

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post #2121 of 2533 Old 07-18-2017, 08:00 AM
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In other words, how do you know what should or shouldn't be corrected at the LP? This is much different than correction of the anechoic response.
At the lower left, it says, "left[FDW]", which I assume means "frequency-dependent windowing". So it's apparently a quasi-anechoic measurement.
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post #2122 of 2533 Old 07-18-2017, 08:21 AM
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It says at "@ listening position" on the graph
Good call. You read better than me lol

If so, that is impressive at 1/48 smoothing. I'm having trouble believing it.
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post #2123 of 2533 Old 07-18-2017, 08:33 AM
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Hi again Floyd, can you or John elaborate on the "Sculptured Surround System Sound System" provided by JVC for Samsung Cinema LED screen installed in Super S theater in South Korea? If we are indeed going with fixed LED screens in the future what does JBL have planned/in store for its parent company Samsung?, or for any future fixed LED or solid screen installs?
Samsung has its own well equipped loudspeaker development group - led by and significantly populated by ex Harman engineers. It is a few miles from Northridge here in California. Now that we are all "one big happy family" it is not surprising that there are joint discussions about loudspeaker solutions for giant flat panel display systems. However, for the majority of home theaters conventional loudspeakers positioned beside, above and below will satisfy demand for some time yet.

As I watch the spectacular images on our new LG OLED65C7 it is easy to imagine the impact of a "really" large one. Screen reflections are an issue, but as in so many things, humans adapt. I see them when I look for them, but otherwise I "look through" them, just as I "listen through" well mannered rooms. In that respect front projection wins handily . . . but those blacks are stunning!
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post #2124 of 2533 Old 07-18-2017, 08:56 AM
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Depends on what you consider really loud. 95 dB is loud, but not really loud.

This is measured using a stepped pure tone at a very high sound level that is sustained long enough to cause voice coil heating. If this were a broadband signal with a flat spectrum the sound level would be deafening - much higher than 95 dB. In reality, very high frequencies in programs are much lower in amplitude than bass-mids and they are most often transient in nature, so this example (which is from my old measuring system at the NRCC I have to say in fairness) greatly exaggerates the problem. It would have been more realistic to drive the loudspeaker with a broadband noise spectrum shaped to simulate the average energy distribution of different kinds of music and movies and then compare results.

Next lifetime I'll get it right :-). If the power compression shown is a problem, it won't be for long. Hearing aids don't respond well to high sound levels.
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post #2125 of 2533 Old 07-18-2017, 09:04 AM
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This is measured using a stepped pure tone at a very high sound level that is sustained long enough to cause voice coil heating. If this were a broadband signal with a flat spectrum the sound level would be deafening - much higher than 95 dB. In reality, very high frequencies in programs are much lower in amplitude than bass-mids and they are most often transient in nature, so this example (which is from my old measuring system at the NRCC I have to say in fairness) greatly exaggerates the problem. It would have been more realistic to drive the loudspeaker with a broadband noise spectrum shaped to simulate the average energy distribution of different kinds of music and movies and then compare results.

Next lifetime I'll get it right :-). If the power compression shown is a problem, it won't be for long. Hearing aids don't respond well to high sound levels.
Thank you for that clarification! When you say "stepped pure tone", are you speaking of a swept sine signal? Or something different?
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post #2126 of 2533 Old 07-18-2017, 09:37 AM
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Thank you for that clarification! When you say "stepped pure tone", are you speaking of a swept sine signal? Or something different?
No, it was a stepped sine tone. It is a legacy of the measuring equipment that was available at the time - really a programmable oscillator under computer control. Of course we could do swept tone and FFT measurements - They all gave the same answers within their bandwidth limitations. Anechoic chambers are a huge benefit. I'm told that the equipment has not been changed, but even if it has been, the data printouts are still the same and the observations still hold.
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post #2127 of 2533 Old 07-18-2017, 09:55 AM
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Originally Posted by Floyd Toole View Post
This is measured using a stepped pure tone at a very high sound level that is sustained long enough to cause voice coil heating. If this were a broadband signal with a flat spectrum the sound level would be deafening - much higher than 95 dB. In reality, very high frequencies in programs are much lower in amplitude than bass-mids and they are most often transient in nature, so this example (which is from my old measuring system at the NRCC I have to say in fairness) greatly exaggerates the problem. It would have been more realistic to drive the loudspeaker with a broadband noise spectrum shaped to simulate the average energy distribution of different kinds of music and movies and then compare results.

Next lifetime I'll get it right :-). If the power compression shown is a problem, it won't be for long. Hearing aids don't respond well to high sound levels.
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No, it was a stepped sine tone. It is a legacy of the measuring equipment that was available at the time - really a programmable oscillator under computer control. Of course we could do swept tone and FFT measurements - They all gave the same answers within their bandwidth limitations. Anechoic chambers are a huge benefit. I'm told that the equipment has not been changed, but even if it has been, the data printouts are still the same and the observations still hold.
I am guessing it is a matter of finances and not knowledge on their part, but if the NRCC asked you what they needed to be state of the art then what would you recommend?

Also, are you attending Cedia this year?

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post #2128 of 2533 Old 07-18-2017, 10:06 AM
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That is certainly a great looking FR, but is beating the response into submission at the listening position with DSP a good idea? It seems to me that there will be a lot of unnecessary correction that could impact SQ negatively?

In other words, how do you know what should or shouldn't be corrected at the LP? This is much different than correction of the anechoic response.
I think this is gated. That makes more sense now
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post #2129 of 2533 Old 07-18-2017, 10:22 AM
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Originally Posted by Jsin_N View Post
I think this is gated. That makes more sense now
Sure looks like it. Here's the REW documentation on frequency-dependent windowing (FDW, see lower left of notnyt's graph).

Quote:
Originally Posted by REW manual
If Add frequency dependent window is selected, a frequency dependent window (FDW) will be applied to the measurement after the left and right windows have been applied. The width of the FDW is set by the controls to the right and can be specified in cycles or in octaves. If the width is in cycles a 15 cycle window (for example) would have a width of 150 ms at 100 Hz (15 times 10 ms), 15 ms at 1 kHz (15 times 1 ms) and 1.5 ms at 10 kHz (15 times 0.1 ms).
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post #2130 of 2533 Old 07-18-2017, 11:23 AM
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Originally Posted by Ericglo View Post
I am guessing it is a matter of finances and not knowledge on their part, but if the NRCC asked you what they needed to be state of the art then what would you recommend?

Also, are you attending Cedia this year?
The original loudspeaker measurement system that measured on 360 deg. polar and equatorial orbits - the precursor of spinorama - was activated in 1983. It used a PDP11-03 steam era computer (state of the art at the time) and outboard programmable oscillators, voltmeters and analyzers. Impulse responses were incorporated as CPU speed and memory allowed. It was extremely flexible, allowing us to vary the settling time vs. frequency, to calibrate the anechoic chamber at low frequencies, and other things that were not at all common in audio. The digitized raw data could be post processed and displayed in different ways. All of this was important as I was in "learning" mode. There were none of the off-the-shelf computer-based tools we have now. This was 34 years ago.

Now there are many alternatives to collect the raw data. Precision and resolution are not challenges when using a calibrated anechoic chamber. Post processing of the data is as important as collecting the raw data points. At Harman we did our own in-house measurement system with all the macros built in. Ever evolving computers make keeping such a system operational a "business" unto itself, but others have been at work and alternatives now exist.

For example: The new Klippel near-field measurement system can output data in spinorama format. This is a paradigm shifter.

No, I will not be attending CEDIA this year. My lectures have been passed on to others and I have done a lifetime of trade shows. Enough. If anything important happens I'll hear about it :-)
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